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Updated: Sep 30, 2026
Whole Genome Sequencing of Candida glabrata for Detection of Markers of Antifungal Drug Resistance
Published on: December 28, 2017
In vitro activity of rezafungin against bloodstream and intra-abdominal Candida isolates: a large EUCAST-based study
Pilar Escribano1, Jesús Moraga2, Almudena Burillo3
1Clinical Microbiology and Infectious Diseases Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain; Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain; Faculty of Health Sciences - HM Hospitals, Universidad Camilo José Cela, Madrid, Spain.
Objectives:
Large-scale studies including isolates from patients with Candida spp. infections are needed to assess the rezafungin resistance rate in Candida spp. and cross-resistance between rezafungin, and the previous echinocandins micafungin and anidulafungin. The study objective was to assess the in vitro rezafungin activity against bloodstream and intra-abdominal Candida spp. isolates.
Methods:
Incident Candida isolates from patients admitted to 16 hospitals in Madrid between January 2007 and December 2025 were studied (sets 1 and 2), additionally fluconazole or to anidulafungin/micafungin resistant isolates were included (set 3). In vitro rezafungin susceptibility of the 3,869 isolates was evaluated using the EUCAST E.Def. 7.4 methodology, with Tween 20 supplementation of the broth. Isolates classified as resistant were re-tested and subjected to fks genes sequencing. Rezafungin resistance rates and cross-resistance patterns were determined.
Results:
Rezafungin exhibited in vitro activity against Candida albicans (MIC90 = 0.001 mg/L), C. dubliniensis (MIC90 = 0.004 mg/L), Nakaseomyces glabratus (MIC90 = 0.008 mg/L), C. tropicalis and Clavispora lusitaniae (MIC90 = 0.016 mg/L), whereas reduced activity was observed against Lodderomyces parapsilosis and Meyerozyma guilliermondii (MIC90 = 1 mg/L). Minimum inhibitory concentration distributions displayed a Gaussian pattern. Overall, rezafungin resistance (sets 1 and 2) was identified in 0.76% (n = 28/3,671) of isolates with available rezafungin clinical breakpoints, with rates ranging from 0.13% to 6.25%, the resistance rate for N. glabratus was 2.51%. No statistically significant differences were observed between resistance rates to rezafungin and those to anidulafungin (0.74%; n = 27/3,671) or micafungin (0.49%; n = 18/3,671). Rezafungin activity was not compromised by fluconazole resistance. Among 68 echinocandin-resistant isolates (sets 1-3), most showed cross-resistance to the three echinocandins tested, and 89.7% (n = 61/68) carried fks mutations.
Conclusions:
Rezafungin demonstrated in vitro activity against a large collection of Candida spp. isolates from bloodstream and intra-abdominal infections. Most rezafungin-resistant isolates harboured fks mutations and were also resistant to anidulafungin.
